One of the productive constructions in various manufacturing fields is an N-step flow-shop type production line which is widely used in assembling works for diversified small-quantity production. Frequently, the supply sequence of the products to the N-step flow-shop type production line is manually determined and usually is determined randomly in handling order (in arrival order) or according to a priority determined by the appointed date of delivery. Moreover, although automatic supply sequence determination calculation methods are known, they require a large amount of calculation and do not provide a method for obtaining an optimum solution. As a result, errors in worker assignment occur frequently due to errors in the production supply sequence planning and errors in the estimates of man-power supply.
In order to solve these problems, extensions of the calculation method of a 2-step flow-shop type production line to an N-step type production line have been studied. In particular, Johnson's rule for the 2-step flow-shop type production line is known and is widely used as a production managing method. In addition, for N-step flow-shop type production lines, Petrov's algorithm is famous. These algorithms are described in detail in Katsundo Hitomi, "Production System Engineering", Kyoritsu Publishing Company. In addition, a new method based on a parallel processing computer has been proposed recently. Details of the new method are disclosed in, for example, "Parallel Algorithm for Minimization of Total Required Time in Flow-Shop Scheduling and Realization Thereof On nCUBE2", Information Processing Engineers Association, Software Engineering Institute, material 87-6 (1992.9.29), pp. 51-57.
For the problem of determining a product supply sequence for a production line, the following apparatuses and methods have been proposed.
(1) Japanese Patent Application No. S63-323495, for "Deciding Method For Production Order In Inclusion Production Line" (Patent application laid-open No. H2-172658, Jul. 4, 1990) PA0 (2) Japanese Patent Application No. H1-159752, for "Input Order Planning Method For FMS Production Line" (Patent Application Laid-open No. H3-26448, Feb. 5, 1991) PA0 (3) Japanese Patent Application No. H1-182580, for "Estimating Simulation Method In Production Line" (Patent Application Laid-open No. H3-49853, Mar. 4, 1991) PA0 (4) Japanese Patent Application No. H1-182886, for "Production Schedule Adjusting Method" (Patent Application Laid-open No. H3-49854, Mar. 4, 1991) PA0 (5) Japanese Patent Application No. H2-224555, for "Scheduling Method and Apparatus" (Patent Application Laid-open No. H3-117542, May 20, 1991) PA0 (6) Japanese Patent Application No. H1-282356, for "Synchronous Production Scheduling Planning Device" (Patent Application Laid-open No. H3-149162, Jun. 25, 1991) PA0 (7) Japanese Patent Application No. H1-305352, for "Method And Device For Planning Production Program" (Patent Application Laid-open No. H3-166047, Jul. 18, 1991) PA0 (8) Japanese Patent Application No. H1-335812, for "Production Planning Preparation Method" (Patent Application Laid-open No. H3-196948, Aug. 28, 1991) PA0 (9) Japanese Patent Application No. H2-127678, for "Method And Device For Calculation Of Necessary Personnel For Production Line" (Patent Application Laid-open No. H4-25353, Jan. 29, 1992) PA0 (10) Japanese Patent Application No. H2-220023, for "Production Sequency Planning Method" (Patent Application Laid-open No. H4-105855, Apr. 7, 1992) PA0 (11) Japanese Patent Application No. H2-220970, for "Production Sequence Decision Method" (Patent Application Laid-open No. H4-105856, Apr. 7, 1992) PA0 (12) Japanese Patent Application No. H2-222223, for "Scheduling Device" (Patent Application Laid-open No. H4-105857, Apr. 7, 1992) PA0 (13) Japanese Patent Application No. H2-190887, for "Method and Apparatus for Modifying Production Schedule" (Patent Application Laid-open No. H4-82659, Mar. 16, 1992) PA0 (14) Japanese Patent Application No. H2-197403, for "Preparation Of Production Program" (Patent Application Laid-open No. H4-82660, Mar. 16, 1992) PA0 (15) Japanese Patent Application No. H2-197404, for "Changing Method For Production Program" (Patent Application Laid-open No. H4-82661, Mar. 16, 1992)
This application relates to a method for determining a production sequence by obtaining a productive priority by referencing a product request information and an indication information from a production indicator device to knowledge data stored in a memory device. PA1 This application relates to a method for stabilizing production by predicting which work piece input will cause a jig shortage and an associated delay for mounting and dismounting the jigs and subsequently employing a supply sequence in which the occurrence of such phenomena is minimized. PA1 This application relates to a method for simulating the production flow line for a plurality of flow production lines having fixed processing sequences and fixed processing times. PA1 This application relates to a method for decreasing the number of unfinished products by calculating a total production load quantity for a plurality of kinds of work pieces, and thereafter calculating a ratio representing the number of work pieces which occupy the total production load quantity. PA1 Scheduling is performed automatically by using rules in a knowledge base. PA1 This application relates to a method for obtaining a production schedule by assigning the respective assembling times of a product to respective production lines every unit of which is an integer multiple of a predetermined minimum working hour. PA1 This application relates to a method for planning a production schedule by assigning start days of respective processings while averaging the number of productions on the basis of the number of productive capability per day and the optimum number of processings. PA1 This application relates to a production planning preparation method by which neck steps are selected and a production schedule is produced such that waiting time becomes minimum. PA1 This application relates to a method by which the number of workers necessary for production is calculated by referencing a total number of man hours required by a production and the number of committable man hours. PA1 This application relates to a method for calculating an expected value of production by assigned time period by dividing the number of productions within a production time period by a date of production, the number of productions per day is obtained by summing them of respective days, spaces corresponding to productions already made are provided and products to be placed every space are determined by averaging. PA1 This application relates to a method for improving productivity. Initially, the products are classified in a plurality of groups according to the duration of a production required period and a production sequence is determined such that products of a plurality of kinds do not exist in mixed state in each of the classifications. Then, a production sequence is determined by averaging them between the classified groups. PA1 This application relates to a device for achieving lot scheduling at high speed by comparing the service starting time and finish time of a device or device information with the process startable time of an execution process, and determining the process starting time and ending time of the execution process. PA1 A work is displayed by a model which is a combination of partial works each having a constant amount of work and the partial works are interactively and graphically modified while constraining configuration of partial work, relation between partial works, and position thereof. PA1 This application relates to a method for producing a production schedule by setting a production schedule reservation table in which the producability of a facility per unit time, production time, and appointed date of delivery are made correspondent on a memory and performing a production assignment of products by modifying values of the production schedule reservation table. PA1 This application relates to a method for modifying a production schedule by calculating a remaining production time from a difference between a scheduled production number for every product type based on data of an assigned production schedule table and an actual production number and utilizing spare time.
As mentioned above, there are a variety of known methods and apparatuses proposed for automatically determining an optimum supply sequence for producing all products within minimum time (minimum number of steps) in the N step flow-shop type production line for diversified small-quantity production. However, in any of them, in order to reduce the amount of calculation by a computer, the N-steps are virtually divided to 2 steps and an optimal supply sequence for such a virtual 2-step flow shop type production line is determined. Therefore, a determined supply sequence is the optimal solution between the virtually divided 2 steps and only rough approximation can be obtained for minimization of a total production time for all products.
Therefore, a need exists for a method of determining a supply sequence for products to be processed in a N-step flow-shop type production line in which the total production time is minimized for all products. Further, a need exists for a method of determining an optimal supply sequence which takes into consideration products to be processed whose assembly has begun but is not complete ("undone products") or products to be processed quickly, either of which may occur in an actual production line. In addition, a need exists for a method of determining an optimal worker arrangement for producing all products in a minimum amount of time on the basis of a result of the automatic supply sequence determination. A need also exists for a method of evaluating the progression of a production schedule and a worker arrangement schedule on the basis of results of the automatic determinations of optimal supply sequence and optimal worker arrangement. A further need exists for a method of determining an optimal supply sequence which permits recalculation of the product supply sequence and the worker arrangement schedule based on a simulation of progressions of the respective steps.